A “session” is a continuous (non-permanent) connection between a user device and a server over a fixed period of time. In one conventional technique, a unique identification number is assigned to each user device which requests to communicate with a server so that the server can identify the user device in subsequent communications. The unique identification number is typically referred to as a session identifier (hereafter, “session ID”). There are, however, drawbacks associated with a security of the session ID, such as when the session ID is leaked.